jdk8-mips64-public/hotspot: src/share/vm/c1/c1_IR.cpp@c124e2e7463e (annotated)

src/share/vm/c1/c1_IR.cpp@c124e2e7463e (annotated)

src/share/vm/c1/c1_IR.cpp

Wed, 31 Aug 2011 16:46:11 -0700

author: never
date: Wed, 31 Aug 2011 16:46:11 -0700
changeset 3099: c124e2e7463e
parent 2349: 5ddfcf4b079e
child 3592: 701a83c86f28
permissions: -rw-r--r--

7083786: dead various dead chunks of code
Reviewed-by: iveresov, kvn

 /*
  * Copyright (c) 1999, 2010, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "c1/c1_Compilation.hpp"
 #include "c1/c1_FrameMap.hpp"
 #include "c1/c1_GraphBuilder.hpp"
 #include "c1/c1_IR.hpp"
 #include "c1/c1_InstructionPrinter.hpp"
 #include "c1/c1_Optimizer.hpp"
 #include "utilities/bitMap.inline.hpp"
 // Implementation of XHandlers
 //
 // Note: This code could eventually go away if we are
 //       just using the ciExceptionHandlerStream.
 XHandlers::XHandlers(ciMethod* method) : _list(method->exception_table_length()) {
   ciExceptionHandlerStream s(method);
   while (!s.is_done()) {
     _list.append(new XHandler(s.handler()));
     s.next();
   }
   assert(s.count() == method->exception_table_length(), "exception table lengths inconsistent");
 }
 // deep copy of all XHandler contained in list
 XHandlers::XHandlers(XHandlers* other) :
   _list(other->length())
 {
   for (int i = 0; i < other->length(); i++) {
     _list.append(new XHandler(other->handler_at(i)));
   }
 }
 // Returns whether a particular exception type can be caught.  Also
 // returns true if klass is unloaded or any exception handler
 // classes are unloaded.  type_is_exact indicates whether the throw
 // is known to be exactly that class or it might throw a subtype.
 bool XHandlers::could_catch(ciInstanceKlass* klass, bool type_is_exact) const {
   // the type is unknown so be conservative
   if (!klass->is_loaded()) {
     return true;
   }
   for (int i = 0; i < length(); i++) {
     XHandler* handler = handler_at(i);
     if (handler->is_catch_all()) {
       // catch of ANY
       return true;
     }
     ciInstanceKlass* handler_klass = handler->catch_klass();
     // if it's unknown it might be catchable
     if (!handler_klass->is_loaded()) {
       return true;
     }
     // if the throw type is definitely a subtype of the catch type
     // then it can be caught.
     if (klass->is_subtype_of(handler_klass)) {
       return true;
     }
     if (!type_is_exact) {
       // If the type isn't exactly known then it can also be caught by
       // catch statements where the inexact type is a subtype of the
       // catch type.
       // given: foo extends bar extends Exception
       // throw bar can be caught by catch foo, catch bar, and catch
       // Exception, however it can't be caught by any handlers without
       // bar in its type hierarchy.
       if (handler_klass->is_subtype_of(klass)) {
         return true;
       }
     }
   }
   return false;
 }
 bool XHandlers::equals(XHandlers* others) const {
   if (others == NULL) return false;
   if (length() != others->length()) return false;
   for (int i = 0; i < length(); i++) {
     if (!handler_at(i)->equals(others->handler_at(i))) return false;
   }
   return true;
 }
 bool XHandler::equals(XHandler* other) const {
   assert(entry_pco() != -1 && other->entry_pco() != -1, "must have entry_pco");
   if (entry_pco() != other->entry_pco()) return false;
   if (scope_count() != other->scope_count()) return false;
   if (_desc != other->_desc) return false;
   assert(entry_block() == other->entry_block(), "entry_block must be equal when entry_pco is equal");
   return true;
 }
 // Implementation of IRScope
 BlockBegin* IRScope::build_graph(Compilation* compilation, int osr_bci) {
   GraphBuilder gm(compilation, this);
   NOT_PRODUCT(if (PrintValueNumbering && Verbose) gm.print_stats());
   if (compilation->bailed_out()) return NULL;
   return gm.start();
 }
 IRScope::IRScope(Compilation* compilation, IRScope* caller, int caller_bci, ciMethod* method, int osr_bci, bool create_graph)
 : _callees(2)
 , _compilation(compilation)
 , _requires_phi_function(method->max_locals())
 {
   _caller             = caller;
   _level              = caller == NULL ?  0 : caller->level() + 1;
   _method             = method;
   _xhandlers          = new XHandlers(method);
   _number_of_locks    = 0;
   _monitor_pairing_ok = method->has_balanced_monitors();
   _start              = NULL;
   if (osr_bci == -1) {
     _requires_phi_function.clear();
   } else {
         // selective creation of phi functions is not possibel in osr-methods
     _requires_phi_function.set_range(0, method->max_locals());
   }
   assert(method->holder()->is_loaded() , "method holder must be loaded");
   // build graph if monitor pairing is ok
   if (create_graph && monitor_pairing_ok()) _start = build_graph(compilation, osr_bci);
 }
 int IRScope::max_stack() const {
   int my_max = method()->max_stack();
   int callee_max = 0;
   for (int i = 0; i < number_of_callees(); i++) {
     callee_max = MAX2(callee_max, callee_no(i)->max_stack());
   }
   return my_max + callee_max;
 }
 bool IRScopeDebugInfo::should_reexecute() {
   ciMethod* cur_method = scope()->method();
   int       cur_bci    = bci();
   if (cur_method != NULL && cur_bci != SynchronizationEntryBCI) {
     Bytecodes::Code code = cur_method->java_code_at_bci(cur_bci);
     return Interpreter::bytecode_should_reexecute(code);
   } else
     return false;
 }
 // Implementation of CodeEmitInfo
 // Stack must be NON-null
 CodeEmitInfo::CodeEmitInfo(ValueStack* stack, XHandlers* exception_handlers)
   : _scope(stack->scope())
   , _scope_debug_info(NULL)
   , _oop_map(NULL)
   , _stack(stack)
   , _exception_handlers(exception_handlers)
   , _is_method_handle_invoke(false) {
   assert(_stack != NULL, "must be non null");
 }
 CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, ValueStack* stack)
   : _scope(info->_scope)
   , _exception_handlers(NULL)
   , _scope_debug_info(NULL)
   , _oop_map(NULL)
   , _stack(stack == NULL ? info->_stack : stack)
   , _is_method_handle_invoke(info->_is_method_handle_invoke) {
   // deep copy of exception handlers
   if (info->_exception_handlers != NULL) {
     _exception_handlers = new XHandlers(info->_exception_handlers);
   }
 }
 void CodeEmitInfo::record_debug_info(DebugInformationRecorder* recorder, int pc_offset) {
   // record the safepoint before recording the debug info for enclosing scopes
   recorder->add_safepoint(pc_offset, _oop_map->deep_copy());
   _scope_debug_info->record_debug_info(recorder, pc_offset, true/*topmost*/, _is_method_handle_invoke);
   recorder->end_safepoint(pc_offset);
 }
 void CodeEmitInfo::add_register_oop(LIR_Opr opr) {
   assert(_oop_map != NULL, "oop map must already exist");
   assert(opr->is_single_cpu(), "should not call otherwise");
   VMReg name = frame_map()->regname(opr);
   _oop_map->set_oop(name);
 }
 // Implementation of IR
 IR::IR(Compilation* compilation, ciMethod* method, int osr_bci) :
     _locals_size(in_WordSize(-1))
   , _num_loops(0) {
   // setup IR fields
   _compilation = compilation;
   _top_scope   = new IRScope(compilation, NULL, -1, method, osr_bci, true);
   _code        = NULL;
 }
 void IR::optimize() {
   Optimizer opt(this);
   if (!compilation()->profile_branches()) {
     if (DoCEE) {
       opt.eliminate_conditional_expressions();
 #ifndef PRODUCT
       if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); }
       if (PrintIR  || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); }
 #endif
     }
     if (EliminateBlocks) {
       opt.eliminate_blocks();
 #ifndef PRODUCT
       if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); }
       if (PrintIR  || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); }
 #endif
     }
   }
   if (EliminateNullChecks) {
     opt.eliminate_null_checks();
 #ifndef PRODUCT
     if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); }
     if (PrintIR  || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); }
 #endif
   }
 }
 static int sort_pairs(BlockPair** a, BlockPair** b) {
   if ((*a)->from() == (*b)->from()) {
     return (*a)->to()->block_id() - (*b)->to()->block_id();
   } else {
     return (*a)->from()->block_id() - (*b)->from()->block_id();
   }
 }
 class CriticalEdgeFinder: public BlockClosure {
   BlockPairList blocks;
   IR*       _ir;
  public:
   CriticalEdgeFinder(IR* ir): _ir(ir) {}
   void block_do(BlockBegin* bb) {
     BlockEnd* be = bb->end();
     int nos = be->number_of_sux();
     if (nos >= 2) {
       for (int i = 0; i < nos; i++) {
         BlockBegin* sux = be->sux_at(i);
         if (sux->number_of_preds() >= 2) {
           blocks.append(new BlockPair(bb, sux));
         }
       }
     }
   }
   void split_edges() {
     BlockPair* last_pair = NULL;
     blocks.sort(sort_pairs);
     for (int i = 0; i < blocks.length(); i++) {
       BlockPair* pair = blocks.at(i);
       if (last_pair != NULL && pair->is_same(last_pair)) continue;
       BlockBegin* from = pair->from();
       BlockBegin* to = pair->to();
       BlockBegin* split = from->insert_block_between(to);
 #ifndef PRODUCT
       if ((PrintIR || PrintIR1) && Verbose) {
         tty->print_cr("Split critical edge B%d -> B%d (new block B%d)",
                       from->block_id(), to->block_id(), split->block_id());
       }
 #endif
       last_pair = pair;
     }
   }
 };
 void IR::split_critical_edges() {
   CriticalEdgeFinder cef(this);
   iterate_preorder(&cef);
   cef.split_edges();
 }
 class UseCountComputer: public ValueVisitor, BlockClosure {
  private:
   void visit(Value* n) {
     // Local instructions and Phis for expression stack values at the
     // start of basic blocks are not added to the instruction list
     if (!(*n)->is_linked() && (*n)->can_be_linked()) {
       assert(false, "a node was not appended to the graph");
       Compilation::current()->bailout("a node was not appended to the graph");
     }
     // use n's input if not visited before
     if (!(*n)->is_pinned() && !(*n)->has_uses()) {
       // note: a) if the instruction is pinned, it will be handled by compute_use_count
       //       b) if the instruction has uses, it was touched before
       //       => in both cases we don't need to update n's values
       uses_do(n);
     }
     // use n
     (*n)->_use_count++;
   }
   Values* worklist;
   int depth;
   enum {
     max_recurse_depth = 20
   };
   void uses_do(Value* n) {
     depth++;
     if (depth > max_recurse_depth) {
       // don't allow the traversal to recurse too deeply
       worklist->push(*n);
     } else {
       (*n)->input_values_do(this);
       // special handling for some instructions
       if ((*n)->as_BlockEnd() != NULL) {
         // note on BlockEnd:
         //   must 'use' the stack only if the method doesn't
         //   terminate, however, in those cases stack is empty
         (*n)->state_values_do(this);
       }
     }
     depth--;
   }
   void block_do(BlockBegin* b) {
     depth = 0;
     // process all pinned nodes as the roots of expression trees
     for (Instruction* n = b; n != NULL; n = n->next()) {
       if (n->is_pinned()) uses_do(&n);
     }
     assert(depth == 0, "should have counted back down");
     // now process any unpinned nodes which recursed too deeply
     while (worklist->length() > 0) {
       Value t = worklist->pop();
       if (!t->is_pinned()) {
         // compute the use count
         uses_do(&t);
         // pin the instruction so that LIRGenerator doesn't recurse
         // too deeply during it's evaluation.
         t->pin();
       }
     }
     assert(depth == 0, "should have counted back down");
   }
   UseCountComputer() {
     worklist = new Values();
     depth = 0;
   }
  public:
   static void compute(BlockList* blocks) {
     UseCountComputer ucc;
     blocks->iterate_backward(&ucc);
   }
 };
 // helper macro for short definition of trace-output inside code
 #ifndef PRODUCT
   #define TRACE_LINEAR_SCAN(level, code)       \
     if (TraceLinearScanLevel >= level) {       \
       code;                                    \
     }
 #else
   #define TRACE_LINEAR_SCAN(level, code)
 #endif
 class ComputeLinearScanOrder : public StackObj {
  private:
   int        _max_block_id;        // the highest block_id of a block
   int        _num_blocks;          // total number of blocks (smaller than _max_block_id)
   int        _num_loops;           // total number of loops
   bool       _iterative_dominators;// method requires iterative computation of dominatiors
   BlockList* _linear_scan_order;   // the resulting list of blocks in correct order
   BitMap     _visited_blocks;      // used for recursive processing of blocks
   BitMap     _active_blocks;       // used for recursive processing of blocks
   BitMap     _dominator_blocks;    // temproary BitMap used for computation of dominator
   intArray   _forward_branches;    // number of incoming forward branches for each block
   BlockList  _loop_end_blocks;     // list of all loop end blocks collected during count_edges
   BitMap2D   _loop_map;            // two-dimensional bit set: a bit is set if a block is contained in a loop
   BlockList  _work_list;           // temporary list (used in mark_loops and compute_order)
   Compilation* _compilation;
   // accessors for _visited_blocks and _active_blocks
   void init_visited()                     { _active_blocks.clear(); _visited_blocks.clear(); }
   bool is_visited(BlockBegin* b) const    { return _visited_blocks.at(b->block_id()); }
   bool is_active(BlockBegin* b) const     { return _active_blocks.at(b->block_id()); }
   void set_visited(BlockBegin* b)         { assert(!is_visited(b), "already set"); _visited_blocks.set_bit(b->block_id()); }
   void set_active(BlockBegin* b)          { assert(!is_active(b), "already set");  _active_blocks.set_bit(b->block_id()); }
   void clear_active(BlockBegin* b)        { assert(is_active(b), "not already");   _active_blocks.clear_bit(b->block_id()); }
   // accessors for _forward_branches
   void inc_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) + 1); }
   int  dec_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) - 1); return _forward_branches.at(b->block_id()); }
   // accessors for _loop_map
   bool is_block_in_loop   (int loop_idx, BlockBegin* b) const { return _loop_map.at(loop_idx, b->block_id()); }
   void set_block_in_loop  (int loop_idx, BlockBegin* b)       { _loop_map.set_bit(loop_idx, b->block_id()); }
   void clear_block_in_loop(int loop_idx, int block_id)        { _loop_map.clear_bit(loop_idx, block_id); }
   // count edges between blocks
   void count_edges(BlockBegin* cur, BlockBegin* parent);
   // loop detection
   void mark_loops();
   void clear_non_natural_loops(BlockBegin* start_block);
   void assign_loop_depth(BlockBegin* start_block);
   // computation of final block order
   BlockBegin* common_dominator(BlockBegin* a, BlockBegin* b);
   void compute_dominator(BlockBegin* cur, BlockBegin* parent);
   int  compute_weight(BlockBegin* cur);
   bool ready_for_processing(BlockBegin* cur);
   void sort_into_work_list(BlockBegin* b);
   void append_block(BlockBegin* cur);
   void compute_order(BlockBegin* start_block);
   // fixup of dominators for non-natural loops
   bool compute_dominators_iter();
   void compute_dominators();
   // debug functions
   NOT_PRODUCT(void print_blocks();)
   DEBUG_ONLY(void verify();)
   Compilation* compilation() const { return _compilation; }
  public:
   ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block);
   // accessors for final result
   BlockList* linear_scan_order() const    { return _linear_scan_order; }
   int        num_loops() const            { return _num_loops; }
 };
 ComputeLinearScanOrder::ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block) :
   _max_block_id(BlockBegin::number_of_blocks()),
   _num_blocks(0),
   _num_loops(0),
   _iterative_dominators(false),
   _visited_blocks(_max_block_id),
   _active_blocks(_max_block_id),
   _dominator_blocks(_max_block_id),
   _forward_branches(_max_block_id, 0),
   _loop_end_blocks(8),
   _work_list(8),
   _linear_scan_order(NULL), // initialized later with correct size
   _loop_map(0, 0),          // initialized later with correct size
   _compilation(c)
 {
   TRACE_LINEAR_SCAN(2, "***** computing linear-scan block order");
   init_visited();
   count_edges(start_block, NULL);
   if (compilation()->is_profiling()) {
     ciMethod *method = compilation()->method();
     if (!method->is_accessor()) {
       ciMethodData* md = method->method_data_or_null();
       assert(md != NULL, "Sanity");
       md->set_compilation_stats(_num_loops, _num_blocks);
     }
   }
   if (_num_loops > 0) {
     mark_loops();
     clear_non_natural_loops(start_block);
     assign_loop_depth(start_block);
   }
   compute_order(start_block);
   compute_dominators();
   NOT_PRODUCT(print_blocks());
   DEBUG_ONLY(verify());
 }
 // Traverse the CFG:
 // * count total number of blocks
 // * count all incoming edges and backward incoming edges
 // * number loop header blocks
 // * create a list with all loop end blocks
 void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) {
   TRACE_LINEAR_SCAN(3, tty->print_cr("Enter count_edges for block B%d coming from B%d", cur->block_id(), parent != NULL ? parent->block_id() : -1));
   assert(cur->dominator() == NULL, "dominator already initialized");
   if (is_active(cur)) {
     TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch"));
     assert(is_visited(cur), "block must be visisted when block is active");
     assert(parent != NULL, "must have parent");
     cur->set(BlockBegin::linear_scan_loop_header_flag);
     cur->set(BlockBegin::backward_branch_target_flag);
     parent->set(BlockBegin::linear_scan_loop_end_flag);
     // When a loop header is also the start of an exception handler, then the backward branch is
     // an exception edge. Because such edges are usually critical edges which cannot be split, the
     // loop must be excluded here from processing.
     if (cur->is_set(BlockBegin::exception_entry_flag)) {
       // Make sure that dominators are correct in this weird situation
       _iterative_dominators = true;
       return;
     }
     assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur,
            "loop end blocks must have one successor (critical edges are split)");
     _loop_end_blocks.append(parent);
     return;
   }
   // increment number of incoming forward branches
   inc_forward_branches(cur);
   if (is_visited(cur)) {
     TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited"));
     return;
   }
   _num_blocks++;
   set_visited(cur);
   set_active(cur);
   // recursive call for all successors
   int i;
   for (i = cur->number_of_sux() - 1; i >= 0; i--) {
     count_edges(cur->sux_at(i), cur);
   }
   for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
     count_edges(cur->exception_handler_at(i), cur);
   }
   clear_active(cur);
   // Each loop has a unique number.
   // When multiple loops are nested, assign_loop_depth assumes that the
   // innermost loop has the lowest number. This is guaranteed by setting
   // the loop number after the recursive calls for the successors above
   // have returned.
   if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
     assert(cur->loop_index() == -1, "cannot set loop-index twice");
     TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops));
     cur->set_loop_index(_num_loops);
     _num_loops++;
   }
   TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id()));
 }
 void ComputeLinearScanOrder::mark_loops() {
   TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops"));
   _loop_map = BitMap2D(_num_loops, _max_block_id);
   _loop_map.clear();
   for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) {
     BlockBegin* loop_end   = _loop_end_blocks.at(i);
     BlockBegin* loop_start = loop_end->sux_at(0);
     int         loop_idx   = loop_start->loop_index();
     TRACE_LINEAR_SCAN(3, tty->print_cr("Processing loop from B%d to B%d (loop %d):", loop_start->block_id(), loop_end->block_id(), loop_idx));
     assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set");
     assert(loop_end->number_of_sux() == 1, "incorrect number of successors");
     assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set");
     assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set");
     assert(_work_list.is_empty(), "work list must be empty before processing");
     // add the end-block of the loop to the working list
     _work_list.push(loop_end);
     set_block_in_loop(loop_idx, loop_end);
     do {
       BlockBegin* cur = _work_list.pop();
       TRACE_LINEAR_SCAN(3, tty->print_cr("    processing B%d", cur->block_id()));
       assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list");
       // recursive processing of all predecessors ends when start block of loop is reached
       if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) {
         for (int j = cur->number_of_preds() - 1; j >= 0; j--) {
           BlockBegin* pred = cur->pred_at(j);
           if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) {
             // this predecessor has not been processed yet, so add it to work list
             TRACE_LINEAR_SCAN(3, tty->print_cr("    pushing B%d", pred->block_id()));
             _work_list.push(pred);
             set_block_in_loop(loop_idx, pred);
           }
         }
       }
     } while (!_work_list.is_empty());
   }
 }
 // check for non-natural loops (loops where the loop header does not dominate
 // all other loop blocks = loops with mulitple entries).
 // such loops are ignored
 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) {
   for (int i = _num_loops - 1; i >= 0; i--) {
     if (is_block_in_loop(i, start_block)) {
       // loop i contains the entry block of the method
       // -> this is not a natural loop, so ignore it
       TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i));
       for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) {
         clear_block_in_loop(i, block_id);
       }
       _iterative_dominators = true;
     }
   }
 }
 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) {
   TRACE_LINEAR_SCAN(3, "----- computing loop-depth and weight");
   init_visited();
   assert(_work_list.is_empty(), "work list must be empty before processing");
   _work_list.append(start_block);
   do {
     BlockBegin* cur = _work_list.pop();
     if (!is_visited(cur)) {
       set_visited(cur);
       TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id()));
       // compute loop-depth and loop-index for the block
       assert(cur->loop_depth() == 0, "cannot set loop-depth twice");
       int i;
       int loop_depth = 0;
       int min_loop_idx = -1;
       for (i = _num_loops - 1; i >= 0; i--) {
         if (is_block_in_loop(i, cur)) {
           loop_depth++;
           min_loop_idx = i;
         }
       }
       cur->set_loop_depth(loop_depth);
       cur->set_loop_index(min_loop_idx);
       // append all unvisited successors to work list
       for (i = cur->number_of_sux() - 1; i >= 0; i--) {
         _work_list.append(cur->sux_at(i));
       }
       for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
         _work_list.append(cur->exception_handler_at(i));
       }
     }
   } while (!_work_list.is_empty());
 }
 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) {
   assert(a != NULL && b != NULL, "must have input blocks");
   _dominator_blocks.clear();
   while (a != NULL) {
     _dominator_blocks.set_bit(a->block_id());
     assert(a->dominator() != NULL || a == _linear_scan_order->at(0), "dominator must be initialized");
     a = a->dominator();
   }
   while (b != NULL && !_dominator_blocks.at(b->block_id())) {
     assert(b->dominator() != NULL || b == _linear_scan_order->at(0), "dominator must be initialized");
     b = b->dominator();
   }
   assert(b != NULL, "could not find dominator");
   return b;
 }
 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) {
   if (cur->dominator() == NULL) {
     TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id()));
     cur->set_dominator(parent);
   } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) {
     TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: computing dominator of B%d: common dominator of B%d and B%d is B%d", cur->block_id(), parent->block_id(), cur->dominator()->block_id(), common_dominator(cur->dominator(), parent)->block_id()));
     assert(cur->number_of_preds() > 1, "");
     cur->set_dominator(common_dominator(cur->dominator(), parent));
   }
 }
 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) {
   BlockBegin* single_sux = NULL;
   if (cur->number_of_sux() == 1) {
     single_sux = cur->sux_at(0);
   }
   // limit loop-depth to 15 bit (only for security reason, it will never be so big)
   int weight = (cur->loop_depth() & 0x7FFF) << 16;
   // general macro for short definition of weight flags
   // the first instance of INC_WEIGHT_IF has the highest priority
   int cur_bit = 15;
   #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--;
   // this is necessery for the (very rare) case that two successing blocks have
   // the same loop depth, but a different loop index (can happen for endless loops
   // with exception handlers)
   INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag));
   // loop end blocks (blocks that end with a backward branch) are added
   // after all other blocks of the loop.
   INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag));
   // critical edge split blocks are prefered because than they have a bigger
   // proability to be completely empty
   INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag));
   // exceptions should not be thrown in normal control flow, so these blocks
   // are added as late as possible
   INC_WEIGHT_IF(cur->end()->as_Throw() == NULL  && (single_sux == NULL || single_sux->end()->as_Throw()  == NULL));
   INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL));
   // exceptions handlers are added as late as possible
   INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag));
   // guarantee that weight is > 0
   weight |= 1;
   #undef INC_WEIGHT_IF
   assert(cur_bit >= 0, "too many flags");
   assert(weight > 0, "weight cannot become negative");
   return weight;
 }
 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) {
   // Discount the edge just traveled.
   // When the number drops to zero, all forward branches were processed
   if (dec_forward_branches(cur) != 0) {
     return false;
   }
   assert(_linear_scan_order->index_of(cur) == -1, "block already processed (block can be ready only once)");
   assert(_work_list.index_of(cur) == -1, "block already in work-list (block can be ready only once)");
   return true;
 }
 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) {
   assert(_work_list.index_of(cur) == -1, "block already in work list");
   int cur_weight = compute_weight(cur);
   // the linear_scan_number is used to cache the weight of a block
   cur->set_linear_scan_number(cur_weight);
 #ifndef PRODUCT
   if (StressLinearScan) {
     _work_list.insert_before(0, cur);
     return;
   }
 #endif
   _work_list.append(NULL); // provide space for new element
   int insert_idx = _work_list.length() - 1;
   while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) {
     _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1));
     insert_idx--;
   }
   _work_list.at_put(insert_idx, cur);
   TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id()));
   TRACE_LINEAR_SCAN(3, for (int i = 0; i < _work_list.length(); i++) tty->print_cr("%8d B%2d  weight:%6x", i, _work_list.at(i)->block_id(), _work_list.at(i)->linear_scan_number()));
 #ifdef ASSERT
   for (int i = 0; i < _work_list.length(); i++) {
     assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set");
     assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist");
   }
 #endif
 }
 void ComputeLinearScanOrder::append_block(BlockBegin* cur) {
   TRACE_LINEAR_SCAN(3, tty->print_cr("appending block B%d (weight 0x%6x) to linear-scan order", cur->block_id(), cur->linear_scan_number()));
   assert(_linear_scan_order->index_of(cur) == -1, "cannot add the same block twice");
   // currently, the linear scan order and code emit order are equal.
   // therefore the linear_scan_number and the weight of a block must also
   // be equal.
   cur->set_linear_scan_number(_linear_scan_order->length());
   _linear_scan_order->append(cur);
 }
 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) {
   TRACE_LINEAR_SCAN(3, "----- computing final block order");
   // the start block is always the first block in the linear scan order
   _linear_scan_order = new BlockList(_num_blocks);
   append_block(start_block);
   assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction");
   BlockBegin* std_entry = ((Base*)start_block->end())->std_entry();
   BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry();
   BlockBegin* sux_of_osr_entry = NULL;
   if (osr_entry != NULL) {
     // special handling for osr entry:
     // ignore the edge between the osr entry and its successor for processing
     // the osr entry block is added manually below
     assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor");
     assert(osr_entry->sux_at(0)->number_of_preds() >= 2, "sucessor of osr entry must have two predecessors (otherwise it is not present in normal control flow");
     sux_of_osr_entry = osr_entry->sux_at(0);
     dec_forward_branches(sux_of_osr_entry);
     compute_dominator(osr_entry, start_block);
     _iterative_dominators = true;
   }
   compute_dominator(std_entry, start_block);
   // start processing with standard entry block
   assert(_work_list.is_empty(), "list must be empty before processing");
   if (ready_for_processing(std_entry)) {
     sort_into_work_list(std_entry);
   } else {
     assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)");
   }
   do {
     BlockBegin* cur = _work_list.pop();
     if (cur == sux_of_osr_entry) {
       // the osr entry block is ignored in normal processing, it is never added to the
       // work list. Instead, it is added as late as possible manually here.
       append_block(osr_entry);
       compute_dominator(cur, osr_entry);
     }
     append_block(cur);
     int i;
     int num_sux = cur->number_of_sux();
     // changed loop order to get "intuitive" order of if- and else-blocks
     for (i = 0; i < num_sux; i++) {
       BlockBegin* sux = cur->sux_at(i);
       compute_dominator(sux, cur);
       if (ready_for_processing(sux)) {
         sort_into_work_list(sux);
       }
     }
     num_sux = cur->number_of_exception_handlers();
     for (i = 0; i < num_sux; i++) {
       BlockBegin* sux = cur->exception_handler_at(i);
       compute_dominator(sux, cur);
       if (ready_for_processing(sux)) {
         sort_into_work_list(sux);
       }
     }
   } while (_work_list.length() > 0);
 }
 bool ComputeLinearScanOrder::compute_dominators_iter() {
   bool changed = false;
   int num_blocks = _linear_scan_order->length();
   assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator");
   assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors");
   for (int i = 1; i < num_blocks; i++) {
     BlockBegin* block = _linear_scan_order->at(i);
     BlockBegin* dominator = block->pred_at(0);
     int num_preds = block->number_of_preds();
     for (int i = 1; i < num_preds; i++) {
       dominator = common_dominator(dominator, block->pred_at(i));
     }
     if (dominator != block->dominator()) {
       TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: updating dominator of B%d from B%d to B%d", block->block_id(), block->dominator()->block_id(), dominator->block_id()));
       block->set_dominator(dominator);
       changed = true;
     }
   }
   return changed;
 }
 void ComputeLinearScanOrder::compute_dominators() {
   TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators));
   // iterative computation of dominators is only required for methods with non-natural loops
   // and OSR-methods. For all other methods, the dominators computed when generating the
   // linear scan block order are correct.
   if (_iterative_dominators) {
     do {
       TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation"));
     } while (compute_dominators_iter());
   }
   // check that dominators are correct
   assert(!compute_dominators_iter(), "fix point not reached");
 }
 #ifndef PRODUCT
 void ComputeLinearScanOrder::print_blocks() {
   if (TraceLinearScanLevel >= 2) {
     tty->print_cr("----- loop information:");
     for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
       BlockBegin* cur = _linear_scan_order->at(block_idx);
       tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id());
       for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
         tty->print ("%d ", is_block_in_loop(loop_idx, cur));
       }
       tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth());
     }
   }
   if (TraceLinearScanLevel >= 1) {
     tty->print_cr("----- linear-scan block order:");
     for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
       BlockBegin* cur = _linear_scan_order->at(block_idx);
       tty->print("%4d: B%2d    loop: %2d  depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth());
       tty->print(cur->is_set(BlockBegin::exception_entry_flag)         ? " ex" : "   ");
       tty->print(cur->is_set(BlockBegin::critical_edge_split_flag)     ? " ce" : "   ");
       tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : "   ");
       tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag)    ? " le" : "   ");
       if (cur->dominator() != NULL) {
         tty->print("    dom: B%d ", cur->dominator()->block_id());
       } else {
         tty->print("    dom: NULL ");
       }
       if (cur->number_of_preds() > 0) {
         tty->print("    preds: ");
         for (int j = 0; j < cur->number_of_preds(); j++) {
           BlockBegin* pred = cur->pred_at(j);
           tty->print("B%d ", pred->block_id());
         }
       }
       if (cur->number_of_sux() > 0) {
         tty->print("    sux: ");
         for (int j = 0; j < cur->number_of_sux(); j++) {
           BlockBegin* sux = cur->sux_at(j);
           tty->print("B%d ", sux->block_id());
         }
       }
       if (cur->number_of_exception_handlers() > 0) {
         tty->print("    ex: ");
         for (int j = 0; j < cur->number_of_exception_handlers(); j++) {
           BlockBegin* ex = cur->exception_handler_at(j);
           tty->print("B%d ", ex->block_id());
         }
       }
       tty->cr();
     }
   }
 }
 #endif
 #ifdef ASSERT
 void ComputeLinearScanOrder::verify() {
   assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list");
   if (StressLinearScan) {
     // blocks are scrambled when StressLinearScan is used
     return;
   }
   // check that all successors of a block have a higher linear-scan-number
   // and that all predecessors of a block have a lower linear-scan-number
   // (only backward branches of loops are ignored)
   int i;
   for (i = 0; i < _linear_scan_order->length(); i++) {
     BlockBegin* cur = _linear_scan_order->at(i);
     assert(cur->linear_scan_number() == i, "incorrect linear_scan_number");
     assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->index_of(cur), "incorrect linear_scan_number");
     int j;
     for (j = cur->number_of_sux() - 1; j >= 0; j--) {
       BlockBegin* sux = cur->sux_at(j);
       assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->index_of(sux), "incorrect linear_scan_number");
       if (!cur->is_set(BlockBegin::linear_scan_loop_end_flag)) {
         assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order");
       }
       if (cur->loop_depth() == sux->loop_depth()) {
         assert(cur->loop_index() == sux->loop_index() || sux->is_set(BlockBegin::linear_scan_loop_header_flag), "successing blocks with same loop depth must have same loop index");
       }
     }
     for (j = cur->number_of_preds() - 1; j >= 0; j--) {
       BlockBegin* pred = cur->pred_at(j);
       assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->index_of(pred), "incorrect linear_scan_number");
       if (!cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
         assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order");
       }
       if (cur->loop_depth() == pred->loop_depth()) {
         assert(cur->loop_index() == pred->loop_index() || cur->is_set(BlockBegin::linear_scan_loop_header_flag), "successing blocks with same loop depth must have same loop index");
       }
       assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors");
     }
     // check dominator
     if (i == 0) {
       assert(cur->dominator() == NULL, "first block has no dominator");
     } else {
       assert(cur->dominator() != NULL, "all but first block must have dominator");
     }
     assert(cur->number_of_preds() != 1 || cur->dominator() == cur->pred_at(0), "Single predecessor must also be dominator");
   }
   // check that all loops are continuous
   for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
     int block_idx = 0;
     assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop");
     // skip blocks before the loop
     while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
       block_idx++;
     }
     // skip blocks of loop
     while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
       block_idx++;
     }
     // after the first non-loop block, there must not be another loop-block
     while (block_idx < _num_blocks) {
       assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order");
       block_idx++;
     }
   }
 }
 #endif
 void IR::compute_code() {
   assert(is_valid(), "IR must be valid");
   ComputeLinearScanOrder compute_order(compilation(), start());
   _num_loops = compute_order.num_loops();
   _code = compute_order.linear_scan_order();
 }
 void IR::compute_use_counts() {
   // make sure all values coming out of this block get evaluated.
   int num_blocks = _code->length();
   for (int i = 0; i < num_blocks; i++) {
     _code->at(i)->end()->state()->pin_stack_for_linear_scan();
   }
   // compute use counts
   UseCountComputer::compute(_code);
 }
 void IR::iterate_preorder(BlockClosure* closure) {
   assert(is_valid(), "IR must be valid");
   start()->iterate_preorder(closure);
 }
 void IR::iterate_postorder(BlockClosure* closure) {
   assert(is_valid(), "IR must be valid");
   start()->iterate_postorder(closure);
 }
 void IR::iterate_linear_scan_order(BlockClosure* closure) {
   linear_scan_order()->iterate_forward(closure);
 }
 #ifndef PRODUCT
 class BlockPrinter: public BlockClosure {
  private:
   InstructionPrinter* _ip;
   bool                _cfg_only;
   bool                _live_only;
  public:
   BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) {
     _ip       = ip;
     _cfg_only = cfg_only;
     _live_only = live_only;
   }
   virtual void block_do(BlockBegin* block) {
     if (_cfg_only) {
       _ip->print_instr(block); tty->cr();
     } else {
       block->print_block(*_ip, _live_only);
     }
   }
 };
 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) {
   ttyLocker ttyl;
   InstructionPrinter ip(!cfg_only);
   BlockPrinter bp(&ip, cfg_only, live_only);
   start->iterate_preorder(&bp);
   tty->cr();
 }
 void IR::print(bool cfg_only, bool live_only) {
   if (is_valid()) {
     print(start(), cfg_only, live_only);
   } else {
     tty->print_cr("invalid IR");
   }
 }
 define_array(BlockListArray, BlockList*)
 define_stack(BlockListList, BlockListArray)
 class PredecessorValidator : public BlockClosure {
  private:
   BlockListList* _predecessors;
   BlockList*     _blocks;
   static int cmp(BlockBegin** a, BlockBegin** b) {
     return (*a)->block_id() - (*b)->block_id();
   }
  public:
   PredecessorValidator(IR* hir) {
     ResourceMark rm;
     _predecessors = new BlockListList(BlockBegin::number_of_blocks(), NULL);
     _blocks = new BlockList();
     int i;
     hir->start()->iterate_preorder(this);
     if (hir->code() != NULL) {
       assert(hir->code()->length() == _blocks->length(), "must match");
       for (i = 0; i < _blocks->length(); i++) {
         assert(hir->code()->contains(_blocks->at(i)), "should be in both lists");
       }
     }
     for (i = 0; i < _blocks->length(); i++) {
       BlockBegin* block = _blocks->at(i);
       BlockList* preds = _predecessors->at(block->block_id());
       if (preds == NULL) {
         assert(block->number_of_preds() == 0, "should be the same");
         continue;
       }
       // clone the pred list so we can mutate it
       BlockList* pred_copy = new BlockList();
       int j;
       for (j = 0; j < block->number_of_preds(); j++) {
         pred_copy->append(block->pred_at(j));
       }
       // sort them in the same order
       preds->sort(cmp);
       pred_copy->sort(cmp);
       int length = MIN2(preds->length(), block->number_of_preds());
       for (j = 0; j < block->number_of_preds(); j++) {
         assert(preds->at(j) == pred_copy->at(j), "must match");
       }
       assert(preds->length() == block->number_of_preds(), "should be the same");
     }
   }
   virtual void block_do(BlockBegin* block) {
     _blocks->append(block);
     BlockEnd* be = block->end();
     int n = be->number_of_sux();
     int i;
     for (i = 0; i < n; i++) {
       BlockBegin* sux = be->sux_at(i);
       assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler");
       BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
       if (preds == NULL) {
         preds = new BlockList();
         _predecessors->at_put(sux->block_id(), preds);
       }
       preds->append(block);
     }
     n = block->number_of_exception_handlers();
     for (i = 0; i < n; i++) {
       BlockBegin* sux = block->exception_handler_at(i);
       assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler");
       BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
       if (preds == NULL) {
         preds = new BlockList();
         _predecessors->at_put(sux->block_id(), preds);
       }
       preds->append(block);
     }
   }
 };
 void IR::verify() {
 #ifdef ASSERT
   PredecessorValidator pv(this);
 #endif
 }
 #endif // PRODUCT
 void SubstitutionResolver::visit(Value* v) {
   Value v0 = *v;
   if (v0) {
     Value vs = v0->subst();
     if (vs != v0) {
       *v = v0->subst();
     }
   }
 }
 #ifdef ASSERT
 class SubstitutionChecker: public ValueVisitor {
   void visit(Value* v) {
     Value v0 = *v;
     if (v0) {
       Value vs = v0->subst();
       assert(vs == v0, "missed substitution");
     }
   }
 };
 #endif
 void SubstitutionResolver::block_do(BlockBegin* block) {
   Instruction* last = NULL;
   for (Instruction* n = block; n != NULL;) {
     n->values_do(this);
     // need to remove this instruction from the instruction stream
     if (n->subst() != n) {
       assert(last != NULL, "must have last");
       last->set_next(n->next());
     } else {
       last = n;
     }
     n = last->next();
   }
 #ifdef ASSERT
   SubstitutionChecker check_substitute;
   if (block->state()) block->state()->values_do(&check_substitute);
   block->block_values_do(&check_substitute);
   if (block->end() && block->end()->state()) block->end()->state()->values_do(&check_substitute);
 #endif
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/c1/c1_IR.cpp@c124e2e7463e (annotated)

src/share/vm/c1/c1_IR.cpp